The concussion is the second in ninth months and fourth in six years for the 28-year-old Shields, who visited a concussion specialist last month.
"I had a chance to visit with Sam," Packers coach Mike McCarthy told ESPN. "He's going through the process. He's making some improvement. He will not be available this week."
Shields, who made three tackles in the season opener, has 245 tackles and eight interceptions in parts of seven campaigns with Green Bay.
The Packers (2-1) have been idle since their 34-27 victory over NFC North rival Detroit on Sept. 25.